Reading .jpg MetaData with JavaScript

I currently am having a hard time trying to read metadata from a .jpg file with javascript. The goal is to store a caption for a particular image in the "title" field of meta data for a .jpg image and read it to display on a web applet. I've looked into ImageInfo and what few examples I could find do not seem to work and I'm finding any kind of documentation for it sparse. At this point I'm completely at a loss at where to look (and yes we really have to use javascript for this) thank you very much in advance.